M.Night released a tweet saying:
My new film is the sequel to #Unbreakable AND #Split. It was always my dream to have both films collide in this third film.
Later Universal added to this by saying the official release date and title; “Glass,” starring Jackson as Elijah Price, aka “Unbreakable’s” Mr. Glass, will arrive in theaters on January 18, 2019.
The official announcement was released later which is:
M. Night Shyamalan brings together the narratives of two of his standout originals—2000’s UNBREAKABLE and last year’s SPLIT—in one explosive, all-new comic-book thriller: GLASS. From UNBREAKABLE, Bruce Willis returns as David Dunn as does Samuel L. Jackson as Elijah Price, known also by his pseudonym Mr. Glass. Joining from SPLIT are James McAvoy, reprising his role as Kevin Wendell Crumb and the multiple identities who reside within, and Anya Taylor-Joy as Casey Cooke, the only captive to survive an encounter with The Beast.
Following the conclusion of SPLIT, GLASS finds Dunn pursuing Crumb’s superhuman figure of The Beast in a series of escalating encounters, while the shadowy presence of Price emerges as an orchestrator who holds secrets critical to both men.
This riveting culmination of his worldwide blockbusters will be produced by Shyamalan and Jason Blum, who also produced the writer/director’s previous two films for Universal. They produce again with Ashwin Rajan and Marc Bienstock, and Steven Schneider, who will executive produce.